Coordinate mapping system for joint treatment

ABSTRACT

A coordinate mapping system is provided for locating a defect in a bone. The system comprises a positioning instrument for controlled delivery of a device to a target site, the instrument comprising a main body and a rail extending from the main body, the rail including a series of indicia corresponding to predefined grid lines, and a template configured to overlay an image of a bone having a defect at the target site, the template including a predefined grid for determining a set of coordinates to locate the target site using the positioning instrument. A method of accessing a target site near a defect in a bone using the radial coordinate mapping system is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/950,114 filed Nov. 19, 2010, and entitled “COORDINATE MAPPING SYSTEMFOR JOINT TREATMENT,” which claims priority to U.S. Provisional No.61/311,632, filed Mar. 8, 2010, and entitled “COORDINATE MAPPING SYSTEMFOR KNEE JOINT REPAIR AND METHODS OF USE,” and U.S. Provisional No.61/263,170 filed Nov. 20, 2009, and entitled “METHOD FOR TREATING JOINTPAIN AND ASSOCIATED INSTRUMENTS,” all of which are herein incorporatedby reference in their entirety.

This application also related to co-pending and co-owned U.S. patentapplication Ser. No. 12/950,355, filed Nov. 19, 2010 and entitled“SUBCHONDRAL TREATMENT OF JOINT PAIN,” the content of which is hereinincorporated in its entirety by reference.

FIELD

The present invention relates to devices and tools for surgicaltreatment of joints, and more particularly to instruments and associatedmethods for the surgical repair and treatment of bone tissue at thesejoints. Even more particularly, the present invention relates to acoordinate mapping system for locating a bone defect using anatomicallandmarks.

BACKGROUND

Human joints, in particular the knee, hip and spine, are susceptible todegeneration from disease, trauma, and long-term repetitive use thateventually lead to pain. Knee pain, for example, is the impetus for awide majority of medical treatments and associated medical costs. Themost popular theory arising from the medical community is that knee painresults from bone-on-bone contact or inadequate cartilage cushioning.These conditions are believed to frequently result from the progressionof osteoarthritis, which is measured in terms of narrowing of the jointspace. Therefore, the severity of osteoarthritis is believed to be anindicator or precursor to joint pain. Most surgeons and medicalpractitioners thus base their treatments for pain relief on this theory.For example, the typical treatment is to administer pain medication, ormore drastically, to perform some type of joint resurfacing or jointreplacement surgery.

However, the severity of osteoarthritis, especially in the knee, hasbeen found to correlate poorly with the incidence and magnitude of kneepain. Because of this, surgeons and medical practitioners have struggledto deliver consistent, reliable pain relief to patients especially ifpreservation of the joint is desired.

Whether by external physical force, disease, or the natural agingprocess, structural damage to bone can cause injury, trauma,degeneration or erosion of otherwise healthy tissue. The resultantdamage can be characterized as a bone defect that can take the form of afissure, fracture, lesion, edema, tumor, or sclerotic hardening, forexample. Particularly in joints, the damage may not be limited to a bonedefect, and may also include cartilage loss (especially articularcartilage), tendon damage, and inflammation in the surrounding area.

Patients most often seek treatment because of pain and deterioration ofquality of life attributed to the osteoarthritis. The goal of surgicaland non-surgical treatments for osteoarthritis is to reduce or eliminatepain and restore joint function. Both non-surgical and surgicaltreatments are currently available for joint repair.

Non-surgical treatments include weight loss (for the overweightpatient), activity modification (low impact exercise), quadricepsstrengthening, patellar taping, analgesic and anti-inflammatorymedications, and with corticosteroid and/or viscosupplements. Typically,non-surgical treatments, usually involving pharmacological interventionsuch as the administration of non-steroidal anti-inflammatory drugs orinjection of hyaluronic acid-based products, are initially administeredto patients experiencing relatively less severe pain or jointcomplications. However, when non-surgical treatments prove ineffective,or for patients with severe pain or bone injury, surgical interventionis often necessary.

Surgical options include arthroscopic partial meniscectomy and loosebody removal. Most surgical treatments conventionally employ mechanicalfixation devices such as screws, plates, staples, rods, sutures, and thelike are commonly used to repair damaged bone. These fixation devicescan be implanted at, or around, the damaged region to stabilize orimmobilize the weakened area, in order to promote healing and providesupport. Injectable or fillable hardening materials such as bonecements, bone void fillers, or bone substitute materials are alsocommonly used to stabilize bone defects.

High tibial osteotomy (HTO) or total knee arthroplasty (TKA) is oftenrecommended for patients with severe pain associated withosteoarthritis, especially when other non-invasive options have failed.Both procedures have been shown to be effective in treating knee painassociated with osteoarthritis.

However, patients only elect HTO or TKA with reluctance. Both HTO andTKA are major surgical interventions and may be associated with severecomplications. HTO is a painful procedure that may require a longrecovery. TKA patients often also report the replaced knee lacks a“natural feel” and have functional limitations. Moreover, both HTO andTKA have limited durability. Accordingly, it would be desirable toprovide a medical procedure that addresses the pain associated withosteoarthritis and provides an alternative to a HTO or TKA procedure.

In current practice, surgeons typically “eyeball” the target site on abone to be repaired. Most conventional targeting and location methodsare crude and provide little guidance to a surgeon during the actualsurgical procedure. Accordingly, it would be desirable to providemethods and systems in which a bone defect can be accurately located andprovide a reference framework that can be used in a surgical procedureirrespective of the approach.

SUMMARY

The present disclosure relates to a coordinate mapping system forlocating a bone defect using anatomical landmarks. The system allows thesurgeon to accurately locate the bone defect with a reference frameworkand access the defect using a positioning instrument during surgery.

In one exemplary embodiment, a coordinate mapping system is provided forlocating a defect in a bone. The system comprises a positioninginstrument for controlled delivery of a device to a target site, theinstrument comprising a main body and a rail extending from the mainbody, the rail including a series of indicia corresponding to predefinedgrid lines, and a template configured to overlay an image of a bonehaving a defect at the target site. The template can include apredefined grid for determining a set of coordinates to locate thetarget site using the positioning instrument. The grid may be, forexampled, a radial grid.

In another exemplary embodiment, a method of accessing a target sitenear a defect on a bone is provided. The method comprises the step ofproviding a template having a predefined grid for determining a set ofcoordinates to locate a target site on a bone having a defect,overlaying the template on an image of the bone, the template beingaligned with an anatomical landmark on the bone, determining a set ofcoordinates of the location of the defect from the grid, providing apositioning instrument for controlled delivery of a device to the targetsite, comprising a main body and a rail extending from the main body,the rail including a series of indicia corresponding to predefined gridlines on the template, aligning the positioning instrument to theanatomical landmark on the bone so that the indicia on the positioninginstrument are consistent with the grid of the template, and accessingthe target site using the set of coordinates.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of thedisclosure and together with the description, serve to explain theprinciples of the disclosure.

FIGS. 1A and 1B show an exemplary embodiment of a radial coordinatetemplate superimposed over a top-down image of a bone, such as thetibia, having a defect;

FIG. 2 conceptually illustrates the implementation of the radialcoordinate template of FIGS. 1A and 1B by an exemplary embodiment of anpositioning instrument of the present disclosure;

FIG. 3A shows a top-down view of an exemplary embodiment of anpositioning instrument of the present disclosure;

FIG. 3B shows a perspective side view of the positioning instrument ofFIG. 3A;

FIG. 4A shows a top-down view of another exemplary embodiment of anpositioning instrument of the present disclosure;

FIG. 4B shows a perspective side view of the positioning instrument ofFIG. 4A;

FIG. 5A shows a top-down view of yet another exemplary embodiment of anpositioning instrument of the present disclosure;

FIG. 5B shows a perspective side view of the positioning instrument ofFIG. 5A;

FIG. 6 shows an exemplary embodiment of a radial coordinate templatesuperimposed over an image of a side view of a bone, such as the femur,having a defect;

FIGS. 7A-7D show an exemplary use of another positioning instrument ofthe present disclosure on a femur; and

FIGS. 8A-8C show an exemplary use of yet another exemplary positioninginstrument of the present disclosure on a femur.

DESCRIPTION OF THE EMBODIMENTS

The present disclosure provides a methodology, devices and instrumentsfor diagnosing and treating joint pain to restore natural joint functionand preserving, as much as possible, the joint's articular and cartilagesurface. Treatments through the joint that violate the articular andcartilage surface often weaken the bone and have unpredictable results.Rather than focusing on treatment of pain through the joint, theembodiments diagnose and treat pain at its source in the subchondralregion of a bone of a joint to relieve the pain. Applicants havediscovered that pain associated with joints, especially osteoarthriticjoints, can be correlated to bone defects or changes at the subchondrallevel rather than, for example, the severity of osteoarthriticprogression of defects at the articular surface level. In particular,bone defects, such as bone marrow lesions, edema, fissures, fractures,hardened bone, etc. near the joint surface lead to a mechanicaldisadvantage and abnormal stress distribution in the periarticular bone,which may cause inflammation and generate pain. By altering the makeupof the periarticular bone (which may or may not be sclerotic) inrelation to the surrounding region, it is possible to change thestructural integrity of the affects bone and restore normal healingfunction, thus leading to a resolution of the inflammation surroundingthe defect.

Applicants have discovered that treatment of the bone by mechanical andbiological means to restore the normal physiologic stress distribution,and restore the healing balance of the bone tissue at the subchondrallevel, is a more effective way of treating pain than conventionaltechniques. That is, treatment can be effectively achieved bymechanically strengthening or stabilizing the defect, and biologicallyinitiating or stimulating a healing response to the defect. Accordingly,the present disclosure provides methods, devices, and systems for asubchondral procedure. This procedure and its associated devices,instruments, etc. are also marketed under the registered trademark nameof SUBCHONDROPLASTY™. The SUBCHONDROPLASTY™ procedure is a response to adesire for an alternative to patients facing partial or total kneereplacement.

In general, the SUBCHONDROPLASTY™ or SCP™ technique is intended to bothstrengthen the bone and stimulate the bone. In SCP™, bone fractures ornon-unions are stabilized, integrated or healed, which results inreduction of a bone defect, such as a bone marrow lesion or edema. Inaddition, SCP™ restores or alters the distribution of forces in a jointto thereby relieve pain. SCP™ can be performed arthroscopically orpercutaneously to treat pain by stabilizing chronic stress fracture,resolving any chronic bone marrow lesion or edema, and preserving, asmuch as possible, the articular surfaces of the joint. SUBCHONDROPLASTY™generally comprises evaluating a joint, for example, by taking an imageof the joint, detecting the presence of one or more subchondral defects,diagnosing which of these subchondral defects is the source of pain, anddetermining an extent of treatment for the subchondral defect. Thepresent technique is particularly suited for treating chronic defects orinjuries, where the patient's natural healing response has not resolvedthe defect. It should be noted, however, that the technique is equallyapplicable to treatment of defects in the subchondral region of bonewhere the defect is due to an acute injury or from other violations. Thepresent disclosure provides several exemplary treatment modalities forSCP™ for the different extents of treatment needed. Accordingly, amedical practitioner may elect to use the techniques and devicesdescribed herein to subchondrally treat any number of bone defects as hedeems appropriate.

In some embodiments, detection and identification of the relevant bonemarrow lesion or bone marrow edema (BML or BME) can be achieved byimaging, e.g., magnetic resonance imaging (MRI), X-ray, manualpalpation, chemical or biological assay, and the like. A T1-weighted MRIcan be used to detect sclerotic bone, for example. Another example isthat a T2-weighted MRI can be used to detect lesions, edemas, and cysts.X-ray imaging may be suitable for early-stage as well as end-stagearthritis. From the imaging, certain defects may be identified as thesource of pain. In general, defects that are associated with chronicinjury and chronic deficit of healing are differentiated from defectsthat result, e.g., from diminished bone density. SCP™ treatments areappropriate for a BML or BME that may be characterized as a bone defectthat is chronically unable to heal (or remodel) itself, which may causea non-union of the bone, stress or insufficiency fractures, andperceptible pain. Factors considered may include, among other things,the nature of the defect, size of the defect, location of the defect,etc. For example, bone defects at the edge near the articular surface ofperiphery of a joint may be often considered eligible for treatment dueto edge-loading effects as well as the likelihood of bone hardening atthese locations. A bone defect caused by an acute injury would generallybe able to heal itself through the patient's own natural healingprocess. However, in such situations where the bone defect is due to anacute injury and either the defect does not heal on its own, or themedical practitioner decides that the present technique is appropriate,SCP™ treatments can be administered on acute stress fractures, BML orBME, or other subchondral defects, as previously mentioned.

According to the embodiments, the SCP™ treatment may continue aftersurgery. In particular, the patient may be monitored for a change inpain scores, or positive change in function. For example, patients arealso checked to see when they are able to perform full weight-bearingactivity and when they can return to normal activity. Of note, ifneeded, the SCP™ procedure can be completely reversed in the event thata patient requires or desires a joint replacement or other type ofprocedure. The SCP™ treatment may also be performed in conjunction withother procedures, such as cartilage resurfacing, regeneration orreplacement, if desired.

The present disclosure provides a number of treatment modalities, andassociated devices, instruments and related methods of use forperforming SUBCHONDROPLASTY™. These treatment modalities may be usedalone or in combination.

In one treatment modality, the subchondral bone in the region of thebone marrow lesion or defect can be strengthened by introduction of ahardening material, such as a bone substitute, at the site. The bonesubstitute may be an injectable calcium phosphate ensconced in anoptimized carrier material. In SCP™, the injected material may alsoserve as a bone stimulator that reinvigorates the desired acute bonehealing activity.

For example, polymethylmethacrylate (PMMA) of calcium phosphate (CaP)cement injections can be made at the defect site. PMMA injection mayincrease the mechanical strength of the bone, allowing it to withstandgreater mechanical stresses. CaP cement injection may also increase themechanical strength of the bone, while also stimulating the localizedregion for bone fracture repair. In one embodiment, the injection can bemade parallel to the joint surface. In another embodiment, the injectioncan be made at an angle to the joint surface. In yet another embodiment,the injection can be made below a bone marrow lesions.

In another treatment modality, the subchondral bone region can bestimulated to trigger or improve the body's natural healing process. Forexample, in one embodiment of this treatment modality, one or more smallholes may be drilled at the region of the defect to increase stimulation(e.g., blood flow, cellular turnover, etc.) and initiate a healingresponse leading to bone repair. In another embodiment, after holes aredrilled an osteogenic, osteoinductive, or osteoconductive agent may beintroduced to the site. Bone graft material, for example, may be used tofill the hole. This treatment modality may create a betterload-supporting environment leading to long term healing. Electrical orheal stimulation may also be employed to stimulate the healing processof a chronically injured bone. Chemical, biochemical and/or biologicalstimulation may also be employed in SCP™. For instance, stimulation ofbone tissue in SCP™ may be enhanced via the use of cytokines and othercell signaling agents to trigger osteogenesis, chondrogenesis, and/orangiogenesis to perhaps reverse progression of osteoarthritis.

In yet another treatment modality, an implantable device may beimplanted into the subchondral bone to provide mechanical support to thedamaged or affected bone region, such as where an insufficiency fractureof stress fracture has occurred. The implant may help create a betterload distribution in the subchondral region. In the knees, the implantmay support tibio-femoral compressive loads. In addition, the implantmay mechanically integrate sclerotic bone with the surrounding healthybone tissue. The implant may be placed in cancellous bone, throughsclerotic bone, or under sclerotic bone at the affected bone region. Theimplant may also be configured as a bi-cortical bone implant. In oneembodiment, one side of the implant can be anchored to the peripheralcortex to create a cantilever beam support (i.e., a portion of theimplant is inserted into bone but the second end stays outside or nearthe outer surface of the bone). The implant may be inserted using aguide wire. In one example, the implant may be inserted over a guidewire. In another example, the implant may be delivered through a guideinstrument.

The implant may further be augmented with a PMMA or CaP cementinjection, other biologic agent, or an osteoconductive, osteoinductiveand/or ostengenic agent. The augmentation material may be introducedthrough the implant, around the implant, and/or apart from the implantbut at the affected bone region, such as into the lower region of a bonemarrow lesion or below the lesion. For example, the implant may act as aportal to inject the augmentation material into the subchondral boneregion.

While each of the above-mentioned treatment modalities may beadministered independent of one another, it is contemplated that anycombination of these modalities may be applied together and in any orderso desired, depending on the severity or stage of development of thebone defect(s). Accordingly, the present disclosure also providessuitable implantable fixation devices for the surgical treatment ofthese altered bone regions or bone defects, especially at thesubchondral level. Applicants have also discovered devices andinstruments that can be used in combination with cements or hardeningmaterials commonly used to repair damaged bone by their introductioninto or near the site of damage, either to create a binding agent,cellular scaffold or mechanical scaffold for immobilization,regeneration or remodeling of the bone tissue.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure. Additional features of thedisclosure will be set forth in part in the description which follows ormay be learned by practice of the disclosure.

Referring now to FIGS. 1A and 1B, embodiments of the present disclosureemploy a coordinate mapping system 10 comprising a template 20 and apositioning instrument 100. In the present examples, the template 20 mayinclude radial coordinates having a radial component and an angularcomponent. This coordinate mapping system 10 may be use to locate a bonedefect with the positioning instrument 100. The coordinate mappingsystem 10 more naturally resembles the various approaches that may beemployed by a surgeon.

In one embodiment, the template 20 utilizes a predefined radial gridthat corresponds to indicia 30 for keyed angles on the positioninginstrument 100. The template may be implemented in tangible form, suchas a transparency, that may be placed over an image of the bone to betreated. The image could be for example, an MRI, an X-ray, other scannedimage, or a combination of one or more of these images. Alternatively,the template 20 may be implemented using software that displays thepredefined grid as an overlay onto a display of the image. The template20 may be customized to account for variations in the dimensions andangle of the image.

While the present examples of templates 20 employ a radial grid, it isunderstood that other types of grids and coordinate systems may beemployed with the template 20 of the present disclosure. Another type ofgrid may include a Cartesian grid, for instance. Further, anycombination of grids or coordinate systems may be utilized incombination together with the present system 10 for even more preciselocation of the bone defect.

FIGS. 1A and 1B show an exemplary embodiment of a template 20 of thecoordinate mapping system 10 superimposed over an image of a bone, suchas the tibia 2, having a defect 8. As shown, the template 20 comprises aseries of radial grid lines 22 spanning 180 degrees. The radial gridlines 22 extend from a common starting point at vertex 24, and terminateat an outer edge 26. Each radial grid line 22 includes a set of intervalmarkings 28 designating a predetermined distance or length. In addition,the radial grid lines 22 are labeled by indicia 30.

As shown for one embodiment, the radial grid lines 22 may be distributedin 15 degree intervals. However, it is understood that the radial gridlines 22 may be separated by other degrees of intervals, such as 5, 10,20, etc. degree intervals as appropriate for the surgical application ofthe system 10.

Interval markings 28 on each of the radial grid lines 22 may serve as aconvenient indicator of distance from either the vertex 24 or the outeredge 26. The interval markings 28, for example, may represent apredetermined distance of 2, 5, or 10 mm, for example.

To implement the coordinate mapping system 10, the template 20 ispositioned such that its vertical grid line G-A aligns with the tubercle6 of tibia 2, as shown in FIGS. 1A and 1B. Depending on the desiredapproach angle (e.g., medial, lateral, etc.), the horizontal grid lineA-G of template 20 may be adjusted up or down until the defect 8 fallswithin the desired coordinates represented by the angular position ofthe two most adjacent grid lines 22 as well as the interval markings 28of the closest of the two grid lines 22. For example, in FIG. 1A thedefect 8 can be located along grid line F, which provides a relativelyshallow angle of approach. Alternatively, in FIG. 1B, the horizontalline A-G of the template 20 is moved down, and the same defect 8 can belocated between grid lines C and D, which provides a relatively widerangle of approach.

FIG. 2 conceptually illustrates the implementation of the template 20 ofFIGS. 1A and 1B onto a positioning instrument 100 of the coordinatemapping system 10 of the present disclosure. For purposes of clarity,certain portions of the template 20 are not shown to allow more spacefor viewing. As can be seen, the positioning instrument 100 comprises amain body 102 from which extends an arm 104 that terminates at contactpad 106 configured to seat against tubercle 6. Of note, the verticalaxis G-A of the template 20 is aligned with the central axis of arm 104.The positioning instrument 100 also includes a rail 140 that extendsfrom the main body 102. As shown, the outer edge 26 of the template 20matches the outer surface 142 of rail 140. In some embodiments, theouter edge 26 of the template 20 can be matched to the inner surface 144of the rail 140.

In use, the template 20 provides a mechanism for determining a set ofthree coordinates for locating the defect 8 based on the patient's ownanatomy (i.e., tubercle). For example, as shown in FIG. 2, the template20 indicates a first coordinate, distance d₁, represented by the numberof interval markings 28 between the outer edge 26 to tubercle 6 alongvertical axis G-A. The second coordinate may represent the angularcomponent corresponding to radial grid line 22 as indicated by theindicia labeled “E” in this example. The third coordinate may representthe distance d₂ represented by the number of interval markings 28between the outer edge 26 to the location of the defect 8 along the “E”radial grid line 22. Accordingly, the example shown in FIG. 2 may have acoordinate set of 2-60-2.5.

FIGS. 3A and 3B illustrate in greater detail the positioning instrument100 of coordinate mapping system 10. As shown in FIG. 3B, thepositioning instrument 100 may further include a brace component 120.The brace component 120 may comprise a shaft 122 hinged to brace 126.The brace 126 may pivot relative to the shaft 122, which can also beadjusted relative to the main body 102 such that the brace can beadjusted to accommodate and bear against the patient's leg.

As also shown, the rail 140 may be circular. However, it is understoodthat the rail 140 may be configured with any other shape. The height ofthe rail 140 may be adjustable relative to the main body 102. In oneembodiment, a pointer or indicator (not shown) could be provided thatpoints to the joint from the vertically adjustable portion of the body102 that can be visible with use of a C-arm during surgery. The surgeonwould align the pointer with a C-arm visible landmark such as the jointline by adjusting the vertical location of the upper portion of theinstrument 100.

Rail 140 may comprise an open slot 146 for receiving an alignment guide150. Though not shown, the alignment guide 150 may have a protrusion ortab that allows it to seat within and slide inside the open slot 146.The alignment guide 150 may also include device portals 152 forreceiving a device, as well as tool-receiving holes 154 for receiving atool such as a pin 50, for example. The device portals 152 may bearranged parallel to each other. It is understood that these portals 152may be provided in other arrangements such as in an arc pattern or theseportals 152 may be angled to converge.

In one embodiment, the rail 140 may extend at an angle to a transverseplane of the tibia 2. The angle could be in the range of about 1 to 15degrees, more preferably about 2 to 10 degrees, and even more preferablyabout 3 to 7 degrees. In one example, the rail 140 may be configured toextend at an angle of about 7 degrees to a transverse plane of thetibial plateau. This slight angle enables the rail 140 to be orientedparallel to the tibial plateau (which typically has a natural, inherentslope), thereby allowing the user to have instrumentation that bettermatches the natural contours of the bone to be treated and which allowsfor the correct angular access to the target site. Accordingly, theangular orientation of the rail 140 allows the user a greater angularopening to access the bone clear of ligament and other surrounding softtissue, and prevents inadvertent angular insertion of any instruments ordevices through cartilage or other unintended bone or soft tissue,causing damage to the joint.

FIGS. 4A and 4B illustrate another exemplary embodiment of a positioninginstrument 100 whereby there are two main bodies 102 on either end ofthe rail 140, each main body 102 having an arm 104 with contact pad 106for seating against the tibia 2. As further shown, the arms 104 may beconfigured to extend through the contact pads 106 and into the tibia 2in order to secure the positioning instrument 100 to the bone.

FIG. 5A and FIG. 5B show another exemplary embodiment of a positioninginstrument 100 in which the arm 104 is adjustable in height along thelength of main body 102. An optional pointer or indicator (not shown)could be provided on the body 102 that points to the joint such thatC-arm imaging can be used for vertical positioning of the instrument 100during surgery. The pointer would be aligned with anatomy seen underC-arm such as the joint line, for example.

In this example, the rail 140 may be provided with a series of portals148 that may be used as an alternative to the device portals 152 ofalignment guide 150. Accordingly, in this embodiment no alignment guide150 would be necessary and the surgeon could insert a device or tooldirectly through the rail 140 by way of these portals 148.

In one embodiment, the rail 140 could be configured to slidably adjustin the medial lateral direction with respect to the main body 102 toallow for fine tuning adjustment of the system 100. The adjustment wouldcorrespond to a medial or lateral shift of the template 20 from the G-Avertical line. In addition, the rail 140 could be straight instead ofcurved, and angled (i.e., angled linear rail), such that the portals 148are parallel in arrangement. This would allow the use of a rotated X-Ycoordinate grid on the template 20 rather than a radial grid. The linearrail 140 could be configured to angularly adjust relative to the mainbody 102. The main body 102 could be stabilized with a plurality offixation pins to the bone, or additional arms 104 may be provided on thepositioning instrument 100 for more stability as desired.

FIG. 6 shows an exemplary embodiment of a template 20′ configured foruse with a femur 4. As shown, this template 20′ is superimposed over animage of a side view of the femur 4 having a defect 8. Similar totemplate 20, the femoral template 20′ comprises again a series of radialgrid lines 22 spanning 180 degrees. Of course, it is understood that thetemplate 20 may be configured with radial grid lines 22 that span anyvariety of degrees, such as for example 90, 270, 360, etc. as desired.The radial grid lines 22 extend from a common starting point at vertex24, and terminate at an outer edge 26. In this embodiment, the radialgrid lines 22 may be distributed in 18 degree intervals represented byindicia 30 labeled A to F.

In use, the axis F-A of the femoral template 20′ is aligned with theaxis 12 of the femur 4. The axis F-A is central to the distal portion ofthe shaft of the femur 4. Like template 20, the femoral template 20′provides for a set of three coordinates for locating the defect 8 in thefemur 4 using the patient's own anatomical landmarks (i.e., axis offemoral shaft). For example, as shown in FIG. 6, the template 20′indicates a first coordinate, distance d₃, represented by the number ofinterval markings 28 between the vertex 24 to the joint line 14. Thesecond coordinate may represent the angular component corresponding toradial grid line 22 as indicated by the indicia labeled “C” in thisexample. The third coordinate may represent the distance d₄ representedby the number of interval markings 28 between the vertex 24 to thelocation of the defect 8 along the “C” radial grid line 22. Accordingly,the example shown in FIG. 6 may have a coordinate set of 8-36-7.25,representing radial grid components and an angular component.

FIGS. 7A-7D show an exemplary use of another positioning instrument 200of the present disclosure on a femur 4. As shown, the positioninginstrument 200 may comprise an elongate body 202 terminating in a hub208. The elongate body 202 may be attached along a portion of its lengthto braces 204, as illustrated in FIGS. 7A to 7D. Braces 204 areconfigured for use with a lower limb, such as a lower leg portion. It isunderstood, however, that other mechanisms may be employed instead ofbraces 204, such as for example, straps for securing the positioninginstrument 200 to a lower leg portion.

Tool-engaging holes 206 may also be provided on the elongate body 202for receiving a tool such as a pin 50. In use, the center C₁ of hub 208is placed at a distance d₃ from joint line 14 of the femur 4, asindicated by template 20′ (see FIGS. 7A and 7B). In one example, aslidable arm 210 having an open-ended slot 212 for easy removal may beemployed to position the elongate body 202 such that the center C₁ ofhub 208 is a distance d₃ from the joint line 14, which can be determinedfrom an anterior-posterior view of a C-arm image during the surgery. Theelongate body 102 is aligned with the axis 12 of the femoral shaft. Pins50 may be placed in order to secure the elongate body 102 to the femur 4along its axis 12, as shown. After the elongate body 102 is secured, theslidable arm 210 may be removed, as shown in FIGS. 7C and 7D.

Extending from the hub 208 is a linear rail 220 at the angle specifiedby template 20′. The linear rail 220 comprises markings 224 along acircular portion 222 with a center C₂ that aligns with the center C₁ ofhub 208. The linear rail 220 is configured to cooperate with analignment guide 250. Alignment guide 250 may be configured with a slotto slidably receive linear rail 220, as shown. The alignment guide 250may be positioned a distance d₄ from the center C₁ of hub 208. As shown,the alignment guide 250 may include device portals 252 that are arrangedparallel to each other. It is understood that these portals 252 may beprovided in other arrangements such as in an arc pattern.

The alignment guide 250 serves as a jig, or a box/frame for guiding adevice to the defect. Each portal 252 has a predetermined distance andspatial relationship relative to the other portals 252. The portals 252serve as spatial references or orientation or location markers for theclinician, and are configured to provide accurate and controlleddelivery of a device to the defect. The portals 64 may be configured atany desired angle relative to the alignment guide 250. In oneembodiment, the portals 252 may be angularly configured to guide, ordirect, the device in a parallel direction relative to the top of thebone being treated, for example. In addition, the device portals 252 caninclude an anti-rotation feature (not shown). For example, the deviceportals 252 may be keyed, or shaped with a specific configuration thatmatches with a shape configuration of the device to be inserted. Thekeyed device portals 252 allow the device to enter and to move freely ina linear direction in and out of the portals 252, all the whilepreventing free rotation thereabout. Thus, the anti-rotation featureprovides a further level of control for the clinician.

FIGS. 8A-8C show yet another positioning instrument 200′ of the presentdisclosure on a femur 4. Positioning instrument 200′ is similar instructure to positioning instrument 200′ described above, with likeelements having the same reference numerals followed by the mark “′”.However, unlike positioning instrument 200, positioning instrument 200′may have a relatively short main body 202′ for use without braces.Instead, main body 202′ may include one or more tool-engaging holes 206′for receiving a tool such as pin 50. These pins 50 may extend throughthe tool-receiving holes 206′ of the main body 202′ and into the femur 4to secure the instrumentation to the bone. In addition, the center C₁ ofhub 208′, along with the center C₂ of circular portion 222′ of thelinear rail 220′ may include a tool-engaging hole 206 for also receivinga tool such as a pin 50, as shown in FIGS. 8A-8C.

In use, the positioning instrument 200′ may be aligned to an anatomicallandmark similar to positioning instrument 200. In the case of thisfemur 4, the positioning instrument 200′ may be aligned to the adductortubercle on the distal femur, as shown. Pins 50 may be placed throughthe tool-engaging holes 206′ of the c_(e)nte_(r)s C₁, C₂ of hub 208′ andcircular portion 222′ of the main body 202′ and linear rail 220′,respectively. These pins 50 may extend through the open-ended slot 212′of the slidable arm 210′ and into bone for securing the instrument 200′in place (see FIG. 8B). Similar to FIGS. 7A-7D, the slidable arm 210′ ofinstrument 200′ may be aligned to the joint line 14 of the femur 4 asidentified through, for example, C-arm imaging during surgery. Thepositioning instrument 200′ should be positioned so as to correspond tothe template 20′ for the femur 4, like in the previous example. Thoughnot shown, the slidable arm 210′ may be removed at this point if sodesired.

After the positioning instrument 200′ has been properly aligned andsecured to the femur 4, the linear rail 220′ can be positioned at anangle corresponding to the angular component of the three coordinate setdetermined by the femoral template 20′ to map the location of the defect8 on the femur 4. Next, alignment guide 250′ may be slid onto the linearrail 220′ as shown in FIG. 8C. The alignment guide 250′ may bepositioned such that the device portals 252′ are aligned with the targetsite, or defect 8 according to a radial grid component of the threecoordinate set. Then, one or more devices may then be inserted throughthe device portal 252′ of the guide 250′ and to the defect to effect thedesired treatment. Positioning instrument 200′ may be usedpercutaneously, and may serve as a fluoroscopic percutaneous devicepositioning instrument.

In the examples shown, the device may be a pin 50. However, the term“device” is used herein to refer generally to any number of implantabledevices, materials and instruments suitable for bone treatment and/orrepair. For example, the device may be an implantable device, aninsertion tool, a drill bit, an injection needle, a catheter, or anyother surgical instrument. The device may be marked with indicia orcolored bands representing depth so that the clinician is better able tocontrol the depth into the bone.

The coordinate mapping system 10 of the present disclosure provides theadvantage of precise and repeated access to a target site from a varietyof angles or trajectories. It is contemplated that the system 10 may beused to compact bone tissue at the target site from multiple approaches,or angles. For example, it is possible to use the system 10 to targetthe same area around the defect from different angles to clean upcompressed bone tissue at the target site. By approaching the samedefect using different trajectories, it is possible to create any numberof geometric patterns of compacted bone tissue around or at the targetsite, such as for example, a starburst-like pattern.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of thedisclosure provided herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the disclosure being indicated by the following claims.

What is claimed is:
 1. A coordinate mapping system comprising: apositioning instrument for controlled delivery of a device to a targetsite, comprising a main body and a rail extending from the main body,the rail including a series of indicia corresponding to predefined gridlines; and a template configured to overlay an image of a bone having adefect at the target site, the template including a predefined grid fordetermining a set of coordinates to locate the target site using thepositioning instrument.
 2. The system of claim 1, wherein the predefinedgrid is a radial grid, and the grid lines are radial grid lines.
 3. Thesystem of claim 1, further including a detachable brace component. 4.The system of claim 1, wherein the rail is circular.
 5. The system ofclaim 4, wherein the target site is a defect on a tibia.
 6. The systemof claim 1, wherein the rail is linear.
 7. The system of claim 6,wherein the target site is a defect on a femur.
 8. The system of claim1, further including an alignment guide attachable to the rail, thealignment guide having one or more device portals for access to thetarget site, the alignment guide being detachable and movable along alength of the rail.
 9. The system of claim 1, wherein the rail includesone or more device portals for access to the target site.
 10. A methodof accessing a target site near a defect in a bone: providing a templatehaving a predefined grid for determining a set of coordinates to locatea target site on a bone having a defect; overlaying the template on animage of the bone, the template being aligned with an anatomicallandmark on the bone; determining a set of coordinates of the locationof the defect from the grid; providing a positioning instrument forcontrolled delivery of a device to the target site, comprising a mainbody and a rail extending from the main body, the rail including aseries of indicia corresponding to predefined grid lines on thetemplate; aligning the positioning instrument to the anatomical landmarkon the bone so that the indicia on the positioning instrument areconsistent with the radial grid of the template; and accessing thetarget site using the set of coordinates.
 11. The method of claim 10,wherein the bone is a tibia.
 12. The method of claim 11, wherein theanatomical landmark is a tubercle.
 13. The method of claim 10, whereinthe bone is a femur.
 14. The method of claim 13, wherein the anatomicallandmark is a femoral shaft axis.
 15. The method of claim 10, whereinthe grid is a radial grid, and the grid lines are radial grid lines.